Semiconductor structure and fabrication method thereof

Abstract

Semiconductor structure and fabrication method are provided. The semiconductor structure includes: a substrate and a magnetic tunnel junction on the substrate. The magnetic tunnel junction includes: a bottom electromagnetic structure on the substrate, an insulating layer on the bottom electromagnetic structure, and a top electromagnetic structure on the insulating layer. The semiconductor structure further includes a sidewall tunneling layer on sidewall surfaces of the magnetic tunnel junction.

What is claimed is: 
     
       1. A semiconductor structure, comprising:
 a substrate; 
 a magnetic tunnel junction on the substrate, wherein the magnetic tunnel junction includes:
 a bottom electromagnetic structure on the substrate, the bottom electromagnetic structure having at least one sidewall surface, 
 an insulating layer on the bottom electromagnetic structure, the insulating layer having at least one sidewall surface, and 
 a top electromagnetic structure on the insulating layer, the top electromagnetic structure having at least one sidewall surface, the at least one sidewall surface of the bottom electromagnetic structure, the at least one sidewall surface of the insulating layer, and the at least one sidewall surface of the top electromagnetic structure being coplanar with each other along a vertical direction, and sidewall surfaces of the magnetic tunnel junction including the at least one sidewall surface of the bottom electromagnetic structure, the at least one sidewall surface of the insulating layer, and the at least one sidewall surface of the top electromagnetic structure; 
 
 a sidewall tunneling layer directly formed on the sidewall surfaces of the magnetic tunnel junction, the sidewall tunneling layer being made of a material including at least one of boron nitride, magnesium oxide, or aluminum oxide, and sidewall surfaces of the sidewall tunneling layer being parallel to the vertical direction; and 
 a protective layer directly formed on the sidewall surfaces of the sidewall tunneling layer and in contact with the entire sidewall surfaces of the sidewall tunneling layer, the protective layer being made of a material including at least one of silicon oxide, silicon nitride, silicon carbide nitride, silicon nitride boride, or silicon oxynitride, the sidewall tunneling layer being located between the magnetic tunnel junction and the protective layer, and sidewall surfaces of the protective layer being parallel to the vertical direction; 
 wherein a top surface of the protective layer, a top surface of the sidewall tunneling layer, and a top surface of the top electromagnetic structure are coplanar with each other, and a bottom surface of the protective layer, a bottom surface of the sidewall tunneling layer, and a bottom surface of the bottom electromagnetic structure are coplanar with each other. 
 
     
     
       2. The semiconductor structure according to  claim 1 , wherein:
 the sidewall tunneling layer has a thickness ranging from about 1 angstrom to about 20 nanometers. 
 
     
     
       3. The semiconductor structure according to  claim 2 , wherein:
 the sidewall tunneling layer has a thickness ranging from about 1 angstrom to about 5 nanometers. 
 
     
     
       4. The semiconductor structure according to  claim 1 , wherein:
 a conductive layer is provided in the substrate, and the substrate exposes a surface of the conductive layer. 
 
     
     
       5. The semiconductor structure according to  claim 1 , wherein:
 the bottom electromagnetic structure includes:
 a lower electrode layer on the substrate; 
 a lower composite layer on the lower electrode layer; and 
 a lower electromagnetic layer on the lower composite layer. 
 
 
     
     
       6. The semiconductor structure according to  claim 5 , wherein:
 the lower electrode layer is made of a material including at least one of copper, tungsten, aluminum, titanium, titanium nitride, or tantalum; 
 the lower composite layer includes a plurality of conductive layers overlapped each other, and each layer of the plurality of conductive layers is made of a material including at least one of iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, or lanthanum strontium manganese oxygen; and 
 the lower electromagnetic layer is made of a material including at least one of iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, or lanthanum strontium manganese oxygen. 
 
     
     
       7. The semiconductor structure according to  claim 1 , wherein:
 the top electromagnetic structure includes:
 an upper electromagnetic layer on the insulating layer; 
 an upper composite layer on the upper electromagnetic layer; and 
 an upper electrode layer on the upper composite layer. 
 
 
     
     
       8. The semiconductor structure according to  claim 7 , wherein:
 the upper electrode layer is made of a material including at least one of copper, tungsten, aluminum, titanium, titanium nitride, or tantalum; 
 the upper composite layer includes a plurality of conductive layers overlapped each other, and each layer of the plurality of conductive layers is made of a material including at least one of iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, or lanthanum strontium manganese oxygen; and 
 the upper electromagnetic layer is made of a material including at least one of iron, platinum, cobalt, nickel, cobalt iron boron, cobalt iron, nickel iron, or lanthanum strontium manganese oxygen. 
 
     
     
       9. The semiconductor structure according to  claim 1 , wherein:
 the insulating layer is made of a material including at least one of magnesium oxide, aluminum oxide, silicon nitride, silicon oxynitride, hafnium dioxide, or zirconium dioxide. 
 
     
     
       10. A method for forming a semiconductor structure, comprising:
 providing a substrate; 
 forming a magnetic tunnel junction on the substrate, wherein the magnetic tunnel junction includes:
 a bottom electromagnetic structure on the substrate, the bottom electromagnetic structure having at least one sidewall surface, 
 an insulating layer on the bottom electromagnetic structure, the insulating layer having at least one sidewall surface, and 
 a top electromagnetic structure on the insulating layer, the top electromagnetic structure having at least one sidewall surface, the at least one sidewall surface of the bottom electromagnetic structure, the at least one sidewall surface of the insulating layer, and the at least one sidewall surface of the top electromagnetic structure being coplanar with each other along a vertical direction, and sidewall surfaces of the magnetic tunnel junction including the at least one sidewall surface of the bottom electromagnetic structure, the at least one sidewall surface of the insulating layer, and the at least one sidewall surface of the top electromagnetic structure; and 
 
 forming a sidewall tunneling layer directly on the sidewall surfaces of the magnetic tunnel junction, the sidewall tunneling layer being made of a material including at least one of boron nitride, magnesium oxide, or aluminum oxide, and sidewall surfaces of the sidewall tunneling layer being parallel to the vertical direction; and 
 forming a protective layer directly on the sidewall surfaces of the sidewall tunneling layer and in contact with the entire sidewall surfaces of the sidewall tunneling layer, the protective layer being made of a material including at least one of silicon oxide, silicon nitride, silicon carbide nitride, silicon nitride boride, or silicon oxynitride, the sidewall tunneling layer being located between the magnetic tunnel junction and the protective layer, and sidewall surfaces of the protective layer being parallel to the vertical direction; 
 wherein a top surface of the protective layer, a top surface of the sidewall tunneling layer, and a top surface of the top electromagnetic structure are coplanar with each other, and a bottom surface of the protective layer, a bottom surface of the sidewall tunneling layer, and a bottom surface of the bottom electromagnetic structure are coplanar with each other. 
 
     
     
       11. The method according to  claim 10 , wherein forming the sidewall tunneling layer includes:
 forming a magnetic conductive material film on the substrate, a top surface and the sidewall surfaces of the magnetic tunnel junction; and 
 etching back the magnetic conductive material film until a surface of the substrate and the top surface of the magnetic tunnel junction are exposed, to form the sidewall tunneling layer on the surface of the substrate. 
 
     
     
       12. The method according to  claim 11 , wherein:
 forming the magnetic conductive material film includes a physical vapor deposition process, a chemical vapor deposition process, an atomic layer deposition process, or a plasma atomic layer deposition process. 
 
     
     
       13. The method according to  claim 10 , wherein forming the magnetic tunnel junction includes:
 forming a bottom electromagnetic material film on the substrate; 
 forming an insulating film on the bottom electromagnetic material film; 
 forming a top electromagnetic material film on the insulating film; 
 forming a patterned layer on the top electromagnetic material film, and 
 using the patterned layer as a mask, etching the bottom electromagnetic material film, the insulating film, and the top electromagnetic material film, until the surface of the substrate is exposed, so that the etched bottom electromagnetic material film forms the bottom electromagnetic structure, the etched insulating film forms the insulating layer, and the etched top electromagnetic material film forms the top electromagnetic structure, to form the magnetic tunnel junction on the substrate. 
 
     
     
       14. The method according to  claim 13 , wherein forming the insulating film includes:
 forming an insulating material film on the bottom electromagnetic material film; and 
 annealing the insulating material film to form the insulating film. 
 
     
     
       15. The method according to  claim 14 , wherein:
 forming the insulating material film includes a physical vapor deposition process, a chemical vapor deposition process, or an atomic layer deposition process. 
 
     
     
       16. The method according to  claim 10 , wherein forming the protective layer includes:
 forming a protective material film on the surface of the substrate, a top surface of the magnetic tunnel junction, and a top surface and the sidewall surfaces of the sidewall tunneling layer; and 
 etching back the protective material film, until the surface of the substrate and the top surface of the magnetic tunnel junction are exposed, to form the protective layer on the sidewall surfaces of the sidewall tunneling layer.